The next post, also from me, is one completely on-topic and helpful. You can ignore this post, if you so choose.
As a precaution, I would keep an eye on your system. This may have been a fluke...or maybe a warning. A former co-worker's computer did something similar to this, mystery not 100% solved, but we did think about it, as addressed below.
(O/T. Partially off- topic, forgive me.)
Computers that think for themselves...
After repairing his OS (Windows XP), my friend found out that his memory slot had fried, due to a bad memory stick. For two years, only this slot, didn't recognize any memory; he avoided using it. Three months ago (approx.) he used his computers memory in a friends and then put it back into his computer, including a stick in the bad slot. Each memory stick and slot work 100% fine, like it never stopped.
My former roommate had a hard drive just die on him - totally wouldn't work - then, after a few days, he put it back into his case for and it worked great...hasn't faltered since.
Pretty weird how computers act sometimes.
Sorry about the O/T post but this seems to fall within one of those occurances.
Like I said, they could be warning signs for issues in the future, or nothing at all - just thought I would point it out.